The symphony of life, revealed

Using a new imaging technique they developed, scientists have managed to observe and document the vibrations of lysozyme, an antibacterial protein found in many animals. This graphic visualizes the vibrations in lysozyme as it is excited by terahertz light (depicted by the red wave arrow). Credit: Andrea Markelz and Katherine Niessen.

A new imaging technique captures the vibrations of proteins, tiny motions critical to human life

“People have been trying to measure these vibrations in proteins for many, many years, since the 1960s.”

Andrea Markelz, Professor of Physics

University at Buffalo

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Using a new imaging technique they developed, scientists have
managed to observe and document the vibrations of lysozyme, an
antibacterial protein found in many animals. This graphic
visualizes the vibrations in lysozyme as it is excited by terahertz
light (depicted by the red wave arrow). Such vibrations, long
thought to exist, have never before been described in such detail,
said lead researcher Andrea Markelz, a UB physicist. Credit: Andrea
Markelz and Katherine Niessen.

Left to right: Andrea Markelz and Katherine Niessen, two of the
study's University at Buffalo coauthors. Credit: Douglas
Levere

BUFFALO, N.Y. — Like the strings on a violin or the pipes
of an organ, the proteins in the human body vibrate in different
patterns, scientists have long suspected.

Now, a new study provides what researchers say is the first
conclusive evidence that this is true.

Using a technique they developed based on terahertz near-field
microscopy, scientists from the University at Buffalo and
Hauptman-Woodward Medical Research Institute (HWI) have for the
first time observed in detail the vibrations of lysozyme, an
antibacterial protein found in many animals.

The team found that the vibrations, which were previously
thought to dissipate quickly, actually persist in molecules like
the “ringing of a bell,” said UB physics professor
Andrea Markelz, PhD, wh0 led the study.

These tiny motions enable proteins to change shape quickly so
they can readily bind to other proteins, a process that is
necessary for the body to perform critical biological functions
like absorbing oxygen, repairing cells and replicating DNA, Markelz
said.

The research opens the door to a whole new way of studying the
basic cellular processes that enable life.

“People have been trying to measure these vibrations in
proteins for many, many years, since the 1960s,” Markelz
said. “In the past, to look at these large-scale, correlated
motions in proteins was a challenge that required extremely dry and
cold environments and expensive facilities.”

“Our technique is easier and much faster,” she said.
“You don’t need to cool the proteins to below freezing
or use a synchrotron light source or a nuclear reactor — all
things people have used previously to try and examine these
vibrations.”

To observe the protein vibrations, Markelz’ team relied on
an interesting characteristic of proteins: The fact that they
vibrate at the same frequency as the light they absorb.

This is analogous to the way wine glasses tremble and shatter
when a singer hits exactly the right note. Markelz explained: Wine
glasses vibrate because they are absorbing the energy of sound
waves, and the shape of a glass determines what pitches of sound it
can absorb. Similarly, proteins with different structures will
absorb and vibrate in response to light of different
frequencies.

So, to study vibrations in lysozyme, Markelz and her colleagues
exposed a sample to light of different frequencies and
polarizations, and measured the types of light the protein
absorbed.

This technique, developed with Edward Snell, a senior research
scientist at HWI and assistant professor of structural biology at
UB, allowed the team to identify which sections of the protein
vibrated under normal biological conditions. The researchers were
also able to see that the vibrations endured over time, challenging
existing assumptions.

“If you tap on a bell, it rings for some time, and with a
sound that is specific to the bell. This is how the proteins
behave,” Markelz said. “Many scientists have previously
thought a protein is more like a wet sponge than a bell: If you tap
on a wet sponge, you don’t get any sustained
sound.”

Markelz said the team’s technique for studying vibrations
could be used in the future to document how natural and artificial
inhibitors stop proteins from performing vital functions by
blocking desired vibrations.

“We can now try to understand the actual structural
mechanisms behind these biological processes and how they are
controlled,” Markelz said.

“The cellular system is just amazing,” she said.
“You can think of a cell as a little machine that does lots
of different things — it senses, it makes more of itself, it
reads and replicates DNA, and for all of these things to occur,
proteins have to vibrate and interact with one another.”